Unidirectional rotatory pedicle screw and spinal deformity correction device for correction of spinal deformity in growing children

Abstract

A scoliosis correction device includes a first fixed anchor that is adapted to be secured to a vertebra of a spine and a second fixed anchor that is adapted to be secured to a vertebra of a spine. A rotatory anchor includes a head portion, a shank portion that extends from the head portion and is adapted to be secured to a vertebra of a spine, and a sprocket that is supported on the head portion for rotational movement relative thereto. A cable extends from the first fixed anchor to the rotatory pedicle screw to the second fixed anchor. The rotatory anchor may be configured to allow unidirectional movement of the sprocket relative to the head portion. A rigid member may extend between the fixed anchor and an intermediate anchor.

1. A rotatory anchor adapted for use in a scoliosis correcting device comprising:
 a head portion including a sprocket; and 
 a shank portion that extends from the head portion and is adapted to be secured to a vertebra of a spine; 
 wherein the sprocket is supported on the head portion for unidirectional rotational movement relative thereto, wherein the sprocket is adapted to cooperate with a portion of a scoliosis correcting device. 
 
     
     
       2. The rotatory anchor defined in  claim 1  wherein the head portion includes an outer circumferential surface, and wherein the sprocket includes an inner circumferential surface that is supported on the outer circumferential surface of the head portion for rotational movement relative thereto. 
     
     
       3. The rotatory anchor defined in  claim 1  wherein the sprocket has a plurality of radially outwardly extending teeth provided on an outer circumferential surface thereof. 
     
     
       4. The rotatory anchor defined in  claim 1  wherein the head portion includes an outer circumferential surface, and wherein the sprocket includes an inner circumferential surface that is supported on the outer circumferential surface of the head portion for unidirectional rotational movement relative thereto. 
     
     
       5. The rotatory anchor defined in  claim 4  wherein a recess is provided in the outer circumferential surface of the head portion, and wherein at least one ball bearing is provided within the recess that engages the inner circumferential surface of the sprocket to cause the unidirectional rotational movement. 
     
     
       6. The rotatory anchor defined in  claim 4  wherein a plurality of recesses is provided in the outer circumferential surface of the head portion, and wherein at least one ball bearing is provided within each of the recesses that engages the inner circumferential surface of the sprocket to cause the unidirectional rotational movement. 
     
     
       7. A scoliosis correction device comprising:
 a first fixed anchor adapted to be secured to be secured to a vertebra of a spine; 
 a second fixed anchor adapted to be secured to be secured to a vertebra of a spine; 
 a rotatory anchor including a head portion, a shank portion that extends from the head portion and is adapted to be secured to a vertebra of a spine, and a sprocket that is supported on the head portion for rotational movement relative thereto; and 
 a cable extending from the first fixed anchor to the rotatory anchor to the second fixed anchor. 
 
     
     
       8. The scoliosis correction device defined in  claim 7  wherein the head portion includes an outer circumferential surface, and wherein the sprocket includes an inner circumferential surface that is supported on the outer circumferential surface of the head portion for rotational movement relative thereto. 
     
     
       9. The scoliosis correction device defined in  claim 7  wherein the sprocket has a plurality of radially outwardly extending teeth provided on an outer circumferential surface thereof. 
     
     
       10. The scoliosis correction device defined in  claim 7  wherein the sprocket is supported on the head portion for unidirectional rotational movement relative thereto. 
     
     
       11. The scoliosis correction device defined in  claim 7  wherein the head portion includes an outer circumferential surface, and wherein the sprocket includes an inner circumferential surface that is supported on the outer circumferential surface of the head portion for unidirectional rotational movement relative thereto. 
     
     
       12. The scoliosis correction device defined in  claim 11  wherein a recess is provided in the outer circumferential surface of the head portion, and wherein at least one ball bearing is provided within the recess that engages the inner circumferential surface of the sprocket to cause the unidirectional rotational movement. 
     
     
       13. The scoliosis correction device defined in  claim 11  wherein a plurality of recesses is provided in the outer circumferential surface of the head portion, and wherein at least one ball bearing is provided within each of the recesses that engages the inner circumferential surface of the sprocket to cause the unidirectional rotational movement. 
     
     
       14. The scoliosis correction device defined in  claim 7  further including an intermediate anchor that is adapted to be secured to a vertebra of a spine, wherein the cable extends from the first fixed anchor to the intermediate anchor to the rotatory anchor to the second fixed anchor. 
     
     
       15. The scoliosis correction device defined in  claim 14  further including a rigid member that extends between the first fixed anchor and the intermediate anchor. 
     
     
       16. The scoliosis correction device defined in  claim 7  wherein the cable is fixed in position relative to the first fixed anchor and the second fixed anchor and is movable relative to the intermediate anchor. 
     
     
       17. The scoliosis correction device defined in  claim 7  wherein the rotatory anchor is a first rotatory anchor, and further including a second rotatory anchor including a head portion, a shank portion that extends from the head portion and is adapted to be secured to a vertebra of a spine, and a sprocket that is supported on the head portion for rotational movement relative thereto, wherein the cable extends from the first fixed anchor to the first rotatory anchor to the second rotatory anchor to the second fixed anchor. 
     
     
       18. The scoliosis correction device defined in  claim 17  further including an intermediate anchor that is adapted to be secured to a vertebra of a spine, wherein the cable extends from the first fixed anchor to the intermediate anchor to the first rotatory anchor to the second rotatory anchor to the second fixed anchor. 
     
     
       19. A rotatory anchor adapted for use in a scoliosis correcting device comprising:
 a head portion including a sprocket; and 
 a shank portion that extends from the head portion and is externally threaded so as to be adapted to be secured to a vertebra of a spine; 
 wherein the sprocket is supported on the head portion for rotational movement relative thereto, wherein the sprocket is adapted to cooperate with a portion of a scoliosis correcting device.